Final answer:
Nucleosome core particles are isolated from chromatin using salt or acidic extraction, which removes associated proteins, allowing for the study of DNA organization. Salt extraction varies the appearance from beads on a string to a 30 nm solenoid fiber, while acidic extraction targets histones specifically.
Step-by-step explanation:
Nucleosome core particles can be isolated from chromatin through various extraction methods. A widely used method is salt extraction, which dissociates most of the proteins from chromatin. When subjected to low salt concentrations, centrifugation can then separate the DNA-wrapped nucleosomes resembling beads on a string. Under higher salt concentrations, nucleosomes appear coiled together, forming the 30 nm solenoid fiber. Another effective method is acidic extraction, which targets the basic histone proteins specifically, removing them and leaving behind DNA associated with non-histone proteins. Through these techniques, nucleosomes can be extracted and studied to understand the tightly regulated structuring of DNA within the cell nucleus.
An electron microscopy provides a visualization of nucleosome structures, with DNA neatly folded around histone proteins resulting in a "beads on a string" appearance. In the broader context of DNA organization, these nucleosome beads are further compacted into higher-order structures with the addition of non-histone proteins, and during mitosis, this compaction reaches its peak in metaphase chromosomes.